We just got used to the difference between ISIS and ISIL and now President Obama is telling us that there's a terrorist group that's even worse than the Islamic State or Al Qaeda. In fact, before most of us had ever heaven heard of them, we already bombed some of their key locations as part of Tuesday's raid on terror targets in Syria.

But what, or who, is the Khorosan Group and why are we just now hearing about a group that could pose the biggest threat to the homeland in years?

Who They Are

According to reports, Khorasan is a group of veteran Al Qaeda members who've moved to Syria with the goal of launching attacks on the west, and, specifically, the U.S. Unlike the other Qaeda offshoot, ISIL/ISIS, which is focused on creating a caliphate in the Middle East by spreading its reign of terror across Iraq, Syria and beyond, Khorasan is reportedly looking outward for its targets. The group is believed to have been birthed from an alliance between al Qaeda operatives in Syria and some from Qaeda's Yemen-based branch, al Qaeda in the Arabian Peninsula, which is home to many expert bomb makers, according to ABC News. The name refers to greater Afghanistan, parts of central Asia and a province in China and in addition to religious significance it is also shorthand for jihad.

What Were We Trying To Destroy?

The early morning airstrikes on Tuesday were aimed at training camps, an explosives production facility, a communications center and a command and control building, according to a statement from the U.S. military. American forces hoped to surprise Khorasan fighters by mixing in strikes against ISIL targets at the same time.

Are They A Threat To The U.S.?

A senior U.S. official told CNN that Khorasan was an "imminent" threat to the homeland, though another official clarified that no known targets were identified and no attacks were planned in the near future. However, intelligence suggested that the group had obtained materials and were working on new improvised explosive devices that would be hard, if not impossible, to detect, including one made of a nonmetallic device like a toothpaste container or clothes dipped in explosive material. One of the plots could have involved secreting those concealed bombs on commercial airplanes.

Why Are We Just Now Hearing About Them?

Though officials have said they've had their eye on them for a while, the existence of Khorasan was just publicly acknowledged by the Obama administration last week, when U.S. Director of National Intelligence James Clapper said the group was operating in Iraq and Syria and plotting to bring terror to the West. A statement from Central Command described a plan of action to "disrupt the imminent attack plotting against the United States and Western interests."

Who's In Charge?

Among the Quaeda veterans believed to be directing Khorasan's planning is Muhsin al-Fadhi, a 33-year-old Kuwaiti who moved to Syria in April 2013 and worked with the terror group Juabhat al Nusra before splitting from them to form Khorasan and turn his focus to "external" targets, according to CNN. Al Fadhi is believed to have been involved in plotting suicide attacks against hotels and oil tankers for more than a decade in Yemen, after fighting with the Taliban and al Qaeda in Afghanistan as a teenager. One of the biggest concerns is that Khorasan leaders might have studied with al Qaeda's master bomb maker, Ibrahim al Asiri, who has twice come close to bringing down Western airliners using novel bombing techniques. Al Fadhi was designated as a terrorist by the U.S. in 2005 and is believed to be one of the few people in Osama bin Laden's inner circle who was aware of the 9/11 terror plot.

How Many Fighters Are There?

Though their numbers are believed to be small at this point, perhaps as few as 50, al Fadhi appears to be borrowing a page from ISIL's playbook by using social media to recruit Westerners to the cause in order to train them and send them home to commit acts of terror.